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Out of two solar cookers, one was covered by a plane glass slab and the other was left open. Which of the two solar cookers will be more efficient and why?
Solar cooker is used to cook food with help of sunlight. The sunlight when it shines on the solar cooker the food inside gets cooked due to the absorbed heat from sun rays.
To avoid the escaping of the heat from the solar cooker, solar cooker is covered with glass as sunlight can pass through glass effectively but the heat inside the cooker will not be radiated out.
Hence the solar cooker covered by a plane glass slab will be more efficient as compared to the uncovered one.
A certain form of energy which is not sourced directly or indirectly from the sun and does not cause any pollution is very easily converted into electricity. This form of energy is however, not available everywhere. Moreover, it is technically very difficult and expensive to obtain it. Name the form of energy.
A certain form of energy is available due to the difference in the temperature of water at the surface of the ocean and its deeper levels.
(i) Name the form of energy.
(ii) Is this energy ultimately derived from the sun or not?
(iii) Explain, how this form of energy can be converted into electricity?
Nikhil and Neha went to a remote village in Kerala to meet their grandmother. They were surprised to see bio-gas plant in Mr. Nair’s house in the neighborhood. There was plenty of livestock and the house hold use cooking gas from the plant. Also, their farm had rich vegetation. They contacted sarpanch of the village and convinced him to set up a bio-gas plant for village community.
(i) Mention the values displayed by Mr. Nair. Nikhil and Neha.
(ii) Explain the possible arguments given by Nikhil and Neha to the sarpanch to convince him to set up a bio-gas plant.
Hemant visited his neighboring village, where a bio-gas plant has been installed recently. He was surprised to see the working of the bio-gas plant. He told his village elders about the advantages of setting up a bio-gas plant in their village. Now. Answer the following question:
(i) What are the advantages of a biogas plant?
(ii) Why is a bio-gas plant commonly called as gobar gas plant?
(iii) Why were the villagers are very much impressed with Hemant?